1. Field of the Invention
The present invention relates to an electromagnetic relay. More specifically, the present invention relates to a small-sized electromagnetic relay improved to reduce an internal resistance of a contact circuit as much as possible and to carry a high current to the relay.
2. Description of the Related Art
A conventional small-sized electromagnetic relay of this type will be described with reference to FIG. 11. FIG. 11 is a longitudinal side view that schematically shows an electromagnetic relay 1. An electromagnetic relay 1 shown in FIG. 11 is composed by a yoke 3 built on an insulation base 2 formed by molding, an iron core 4 fixed to the yoke 3, a coil 5 wound around a bobbin (not shown) with the iron core 4 provided in a central portion of the coil 5, an armature 6 provided to be pivotally rotatable about an upper end of the yoke 3 set as a fulcrum, an insulation card 7 provided in front of a lower end of the armature 6 and longitudinally reciprocating to follow rotation of the armature 6, a movable contact piece 8 abutting on a front end of the insulation card 7, having a lower end fixed to the insulation base 2 by a longitudinal movement of the insulation card 7, and provided to be longitudinally pivotally rotatable about the lower end set as a fulcrum, a movable contact 9 provided on an outer side surface of an upper end of the movable contact piece 8, a fixed contact piece 10 provided in front of and in parallel to the movable contact piece 8, a fixed contact 11 provided in rear of an upper end of the fixed contact piece 10 to face the movable contact 9, and a cap 12 that contains the preceding constituent elements.
The electromagnetic relay 1 is constituted as follows. When a power of the coil 5 is turned on or off, the iron core 4 attracts or separates one end of the armature 6 to pivotally rotate the armature 6 about the fulcrum, and to longitudinally move the insulation card 7 on the lower end of the armature 6. In addition, to follow the longitudinal movement of the insulation card 7, the movable contact piece 8 is longitudinally pivotally rotated about its lower end set as the fulcrum, the movable contact 9 provided on the movable contact piece 8 comes in contact with or separates from the fixed contact 11, thereby opening or closing the movable contact 9 and the fixed contact 11.
The movable contact piece 8 has a cantilever structure having the lower end fixed to the insulation base 2. Therefore, the electromagnetic relay of this type is employed if a current capacity is not very large (For example, refer to Patent Literatures 1 to 3: Japanese Patent Application Laid-open Nos. H6-231665, H10-125202, and 2001-93393, respectively).
According to this conventional technique, since the movable contact piece 8 needs to be constituted by a spring plate, an internal resistance of a contact circuit cannot be set low. With a structure in which the movable contact 9 is attached to the movable contact piece 8 so as to reduce the resistance, and in which the movable contact piece 8 is set to have a large thickness and supported by the cantilever spring, the conventional electromagnetic relay disadvantageously, sometimes malfunctions when an impact is applied since the movable contact 9 having a heavy tip end is fixedly provided.